The statements in this section merely provide background information related to the present disclosure. Accordingly, such statements are not intended to constitute an admission of prior art. Poppet valves are widely used in Diesel engines, spark-ignited engines, and other reciprocating piston machines. Valve bridges are commonly used in engines with multiple valves. Diesel engines are widely used in heavy duty vehicles, light duty vehicles, electrical generators, and a variety of other applications. Engine design compression ratio is a compromise between power, economy, emissions, and cold startability. In Diesel engines, the optimum compression ratio for best fuel economy is less than 15:1, whereas the necessary compression ratio for cold starting ranges from 16:1 to 23:1 and depends on the specific design of the engine and its application. This compression ratio range is too high for best economy, lowest emissions and optimum power boost.
Typically, Diesel engines are sized larger than needed for the majority of their service in order to provide reserve power for excessive loads such as hill climbing or passing in the case of road vehicles or to support an unusually high power requirement in the case of stationary power generators or stationary refrigeration vehicles on an especially hot day. Consequently, much of the time the engine is operated at a fraction of its design power capability in particular applications involving extensive idling and/or light load operation such as military surveillance vehicles, idling refrigerator vehicles and stationary electric generators, etc.